The propanediol utilization (pdu) operon of Salmonella enterica serovar typhimurium LT2 includes genes necessary for formation of polyhedral organelles involved in coenzyme B12-dependent 1,2-propanediol degradation
The propanediol utilization (pdu) operon of Salmonella enterica serovar typhimurium LT2 includes genes necessary for formation of polyhedral organelles involved in coenzyme B12-dependent 1,2-propanediol degradation
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DOI：
10.1128/jb.181.19.5967-5975.1999
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发表时间：
1999-10-01
影响因子：
3.2
通讯作者：
Aldrich, HC
中科院分区：
文献类型：
--
作者：
Bobik, TA;Havemann, GD;Aldrich, HC
肠沙门氏菌血清型鼠伤寒杆菌LT2丙二醇利用（pdu）操纵子含有辅酶b -12依赖性分解代谢1,2-丙二醇所需的基因。这里给出了pdu操纵子的完整DNA序列。对先前未发表的pdu DNA序列的分析证实了先前的研究，表明pdu操纵子是通过水平基因转移获得的，并允许鉴定16个假设的基因。这使得pdu操纵子的基因总数达到21个，pdu位点的基因总数达到23个。其中，6个编码功能未知的蛋白质，与GenBank中发现的已知功能序列关系不密切。两种编码蛋白参与运输和调节。6种可能编码1,2-丙二醇降解途径所需的酶。两个编码的蛋白质与那些用于腺苷钴胺（AdoCbl）依赖性二醇脱水酶的再激活相关。其中五种编码的蛋白质与被称为羧基体的多面体细胞器的形成有关，另外两种编码的蛋白质似乎与参与羧基体形成的蛋白质有远亲关系。此外，研究表明肠球菌形成多面体，参与1,2-丙二醇的降解。在丙二醇的好氧或厌氧生长过程中形成多面体，但在其他碳源的生长过程中不会形成多面体。基因测试表明pdu操纵子的基因是多面体形成所必需的，免疫电镜显示adoccl依赖性二醇脱水酶与这些多面体有关。这是第一个与多面体相关的b -12依赖酶的证据。有人提出，多面体由adocbl2依赖的二醇脱水酶（可能还有其他蛋白质）组成，这些蛋白质被包裹在一个与羧酸体外壳相关的蛋白质外壳内。这些不寻常多面体的具体功能尚未确定，但讨论了一些可能性。
The propanediol utilization (pdu) operon of Salmonella enterica serovar Typhimurium LT2 contains genes needed for the coenzyme B-12-dependent catabolism of 1,2-propanediol. Here the completed DNA sequence of the pdu operon is presented. Analyses of previously unpublished pdu DNA sequence substantiated previous studies indicating that the pdu operon was acquired by horizontal gene transfer and allowed the identification of 16 hypothetical genes. This brings the total number of genes in the pdu operon to 21 and the total number of genes at the pdu locus to 23. Of these, six encode proteins of unknown function and are not closely related to sequences of known function found in GenBank. Two encode proteins involved in transport and regulation. Six probably encode enzymes needed for the pathway of 1,2-propanediol degradation. Two encode proteins related to those used for the reactivation of adenosylcobalamin (AdoCbl)-dependent diol dehydratase. Five encode proteins related to those involved in the formation of polyhedral organelles known as carboxysomes, and two encode proteins that appear distantly related to those involved in carboxysome formation. In addition, it is shown that S. enterica forms polyhedral bodies that are involved in the degradation of 1,2-propanediol. Polyhedra are formed during either aerobic or anaerobic growth on propanediol, but not during growth on other carbon sources. Genetic tests demonstrate that genes of the pdu operon are required for polyhedral body formation, and immunoelectron microscopy shows that AdoCbl-dependent diol dehydratase is associated with these polyhedra. This is the first evidence for a B-12-dependent enzyme associated with a polyhedral body. It is proposed that the polyhedra consist of AdoCbl-dependent diol dehydratase (and perhaps other proteins) encased within a protein shell that is related to the shell of carboxysomes. The specific function of these unusual polyhedral bodies was not determined, but some possibilities are discussed.